/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2002             *
 * by the XIPHOPHORUS Company http://www.xiph.org/                  *
 *                                                                  *
 ********************************************************************

 function: simple example decoder
 last mod: $Id: decoder_example.c,v 1.27 2002/07/12 15:07:52 giles Exp $

 ********************************************************************/

/* Takes a vorbis bitstream from stdin and writes raw stereo PCM to
stdout.  Decodes simple and chained OggVorbis files from beginning
to end.  Vorbisfile.a is somewhat more complex than the code below.  */

/* Note that this is POSIX, not ANSI code */

import std.stdio;
import bcd.ogg.ogg;
import bcd.vorbis.codec;

extern (C) void exit(int);

int convbuffer[4096]; /* take 8k out of the data segment, not the stack */
int convsize=4096;

extern void _VDBG_dump();

int main(){
    ogg_sync_state   oy; /* sync and verify incoming physical bitstream */
    ogg_stream_state os; /* take physical pages, weld into a logical
    stream of packets */
    ogg_page         og; /* one Ogg bitstream page.  Vorbis packets are inside */
    ogg_packet       op; /* one raw packet of data for decode */
  
    vorbis_info      vi; /* struct that stores all the static vorbis bitstream
    settings */
    vorbis_comment   vc; /* struct that stores all the bitstream user comments */
    vorbis_dsp_state vd; /* central working state for the packet->PCM decoder */
    vorbis_block     vb; /* local working space for packet->PCM decode */
  
    char *buffer;
    int  bytes;

    /********** Decode setup ************/

    ogg_sync_init(&oy); /* Now we can read pages */
  
    while(1){ /* we repeat if the bitstream is chained */
        int eos=0;
        int i;

        /* grab some data at the head of the stream.  We want the first page
        (which is guaranteed to be small and only contain the Vorbis
        stream initial header) We need the first page to get the stream
        serialno. */

        /* submit a 4k block to libvorbis' Ogg layer */
        buffer=ogg_sync_buffer(&oy,4096);
        bytes=fread(buffer,1,4096,stdin);
        ogg_sync_wrote(&oy,bytes);
    
        /* Get the first page. */
        if(ogg_sync_pageout(&oy,&og)!=1){
            /* have we simply run out of data?  If so, we're done. */
            if(bytes<4096)break;
      
            /* error case.  Must not be Vorbis data */
            fprintf(stderr,"Input does not appear to be an Ogg bitstream.\n");
            exit(1);
        }
  
        /* Get the serial number and set up the rest of decode. */
        /* serialno first; use it to set up a logical stream */
        ogg_stream_init(&os,ogg_page_serialno(&og));
    
        /* extract the initial header from the first page and verify that the
        Ogg bitstream is in fact Vorbis data */
    
        /* I handle the initial header first instead of just having the code
        read all three Vorbis headers at once because reading the initial
        header is an easy way to identify a Vorbis bitstream and it's
        useful to see that functionality seperated out. */
    
        vorbis_info_init(&vi);
        vorbis_comment_init(&vc);
        if(ogg_stream_pagein(&os,&og)<0){ 
            /* error; stream version mismatch perhaps */
            fprintf(stderr,"Error reading first page of Ogg bitstream data.\n");
            exit(1);
        }
    
        if(ogg_stream_packetout(&os,&op)!=1){ 
            /* no page? must not be vorbis */
            fprintf(stderr,"Error reading initial header packet.\n");
            exit(1);
        }
    
        if(vorbis_synthesis_headerin(&vi,&vc,&op)<0){ 
            /* error case; not a vorbis header */
            fprintf(stderr,"This Ogg bitstream does not contain Vorbis "
                    "audio data.\n");
            exit(1);
        }
    
        /* At this point, we're sure we're Vorbis.  We've set up the logical
        (Ogg) bitstream decoder.  Get the comment and codebook headers and
        set up the Vorbis decoder */
    
        /* The next two packets in order are the comment and codebook headers.
        They're likely large and may span multiple pages.  Thus we reead
        and submit data until we get our two pacakets, watching that no
        pages are missing.  If a page is missing, error out; losing a
        header page is the only place where missing data is fatal. */
    
        i=0;
        while(i<2){
            while(i<2){
                int result=ogg_sync_pageout(&oy,&og);
                if(result==0)break; /* Need more data */
                /* Don't complain about missing or corrupt data yet.  We'll
                catch it at the packet output phase */
                if(result==1){
                    ogg_stream_pagein(&os,&og); /* we can ignore any errors here
                    as they'll also become apparent
                    at packetout */
                    while(i<2){
                        result=ogg_stream_packetout(&os,&op);
                        if(result==0)break;
                        if(result<0){
                            /* Uh oh; data at some point was corrupted or missing!
                            We can't tolerate that in a header.  Die. */
                            fprintf(stderr,"Corrupt secondary header.  Exiting.\n");
                            exit(1);
                        }
                        vorbis_synthesis_headerin(&vi,&vc,&op);
                        i++;
                    }
                }
            }
            /* no harm in not checking before adding more */
            buffer=ogg_sync_buffer(&oy,4096);
            bytes=fread(buffer,1,4096,stdin);
            if(bytes==0 && i<2){
                fprintf(stderr,"End of file before finding all Vorbis headers!\n");
                exit(1);
            }
            ogg_sync_wrote(&oy,bytes);
        }
    
        /* Throw the comments plus a few lines about the bitstream we're
        decoding */
        {
            char **ptr=vc.user_comments;
            while(*ptr){
                fprintf(stderr,"%s\n",*ptr);
                ++ptr;
            }
            fprintf(stderr,"\nBitstream is %d channel, %ldHz\n",vi.channels,vi.rate);
            fprintf(stderr,"Encoded by: %s\n\n",vc.vendor);
        }
    
        convsize=4096/vi.channels;

        /* OK, got and parsed all three headers. Initialize the Vorbis
        packet->PCM decoder. */
        vorbis_synthesis_init(&vd,&vi); /* central decode state */
        vorbis_block_init(&vd,&vb);     /* local state for most of the decode
        so multiple block decodes can
        proceed in parallel.  We could init
        multiple vorbis_block structures
        for vd here */
    
        /* The rest is just a straight decode loop until end of stream */
        while(!eos){
            while(!eos){
                int result=ogg_sync_pageout(&oy,&og);
                if(result==0)break; /* need more data */
                if(result<0){ /* missing or corrupt data at this page position */
                    fprintf(stderr,"Corrupt or missing data in bitstream; "
                            "continuing...\n");
                }else{
                    ogg_stream_pagein(&os,&og); /* can safely ignore errors at
                    this point */
                    while(1){
                        result=ogg_stream_packetout(&os,&op);

                        if(result==0)break; /* need more data */
                        if(result<0){ /* missing or corrupt data at this page position */
                            /* no reason to complain; already complained above */
                        }else{
                            /* we have a packet.  Decode it */
                            float **pcm;
                            int samples;
	      
                            if(vorbis_synthesis(&vb,&op)==0) /* test for success! */
                                vorbis_synthesis_blockin(&vd,&vb);
                            /* 
		 
                             **pcm is a multichannel float vector.  In stereo, for
                             example, pcm[0] is left, and pcm[1] is right.  samples is
                             the size of each channel.  Convert the float values
                             (-1.<=range<=1.) to whatever PCM format and write it out */
	      
                            while((samples=vorbis_synthesis_pcmout(&vd,&pcm))>0){
                                int j;
                                int clipflag=0;
                                int bout=(samples<convsize?samples:convsize);
		
                                /* convert floats to 16 bit signed ints (host order) and
                                interleave */
                                for(i=0;i<vi.channels;i++){
                                    int *ptr=&convbuffer[i];
                                    float  *mono=pcm[i];
                                    for(j=0;j<bout;j++){
                                        int val=cast(int) (mono[j]*32767.f);
                                        /* might as well guard against clipping */
                                        if(val>32767){
                                            val=32767;
                                            clipflag=1;
                                        }
                                        if(val<-32768){
                                            val=-32768;
                                            clipflag=1;
                                        }
                                        *ptr=val;
                                        ptr+=vi.channels;
                                    }
                                }
		
                                if(clipflag)
                                    fprintf(stderr,"Clipping in frame %d\n",(vd.sequence));
		
		
                                fwrite(convbuffer,2*vi.channels,bout,stdout);
		
                                vorbis_synthesis_read(&vd,bout); /* tell libvorbis how
                                many samples we
                                actually consumed */
                            }	    
                        }
                    }
                    if(ogg_page_eos(&og))eos=1;
                }
            }
            if(!eos){
                buffer=ogg_sync_buffer(&oy,4096);
                bytes=fread(buffer,1,4096,stdin);
                ogg_sync_wrote(&oy,bytes);
                if(bytes==0)eos=1;
            }
        }
    
        /* clean up this logical bitstream; before exit we see if we're
        followed by another [chained] */

        ogg_stream_clear(&os);
  
        /* ogg_page and ogg_packet structs always point to storage in
        libvorbis.  They're never freed or manipulated directly */
    
        vorbis_block_clear(&vb);
        vorbis_dsp_clear(&vd);
	vorbis_comment_clear(&vc);
        vorbis_info_clear(&vi);  /* must be called last */
    }

    /* OK, clean up the framer */
    ogg_sync_clear(&oy);
  
    fprintf(stderr,"Done.\n");
    return(0);
}
